1 /* $OpenBSD: setmode.c,v 1.13 2004/05/18 02:05:52 jfb Exp $ */ 2 /* $NetBSD: setmode.c,v 1.15 1997/02/07 22:21:06 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1989, 1993, 1994 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Dave Borman at Cray Research, Inc. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)setmode.c 8.2 (Berkeley) 3/25/94"; 39 #else 40 static char rcsid[] = "$OpenBSD: setmode.c,v 1.13 2004/05/18 02:05:52 jfb Exp $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <sys/types.h> 45 #include <sys/stat.h> 46 47 #include <ctype.h> 48 #include <errno.h> 49 #include <signal.h> 50 #include <stdlib.h> 51 #include <unistd.h> 52 53 #ifdef SETMODE_DEBUG 54 #include <stdio.h> 55 #endif 56 57 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */ 58 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */ 59 60 typedef struct bitcmd { 61 char cmd; 62 char cmd2; 63 mode_t bits; 64 } BITCMD; 65 66 #define CMD2_CLR 0x01 67 #define CMD2_SET 0x02 68 #define CMD2_GBITS 0x04 69 #define CMD2_OBITS 0x08 70 #define CMD2_UBITS 0x10 71 72 static BITCMD *addcmd(BITCMD *, int, int, int, u_int); 73 static void compress_mode(BITCMD *); 74 #ifdef SETMODE_DEBUG 75 static void dumpmode(BITCMD *); 76 #endif 77 78 /* 79 * Given the old mode and an array of bitcmd structures, apply the operations 80 * described in the bitcmd structures to the old mode, and return the new mode. 81 * Note that there is no '=' command; a strict assignment is just a '-' (clear 82 * bits) followed by a '+' (set bits). 83 */ 84 mode_t 85 getmode(const void *bbox, mode_t omode) 86 { 87 register const BITCMD *set; 88 register mode_t clrval, newmode, value; 89 90 set = (const BITCMD *)bbox; 91 newmode = omode; 92 for (value = 0;; set++) 93 switch(set->cmd) { 94 /* 95 * When copying the user, group or other bits around, we "know" 96 * where the bits are in the mode so that we can do shifts to 97 * copy them around. If we don't use shifts, it gets real 98 * grundgy with lots of single bit checks and bit sets. 99 */ 100 case 'u': 101 value = (newmode & S_IRWXU) >> 6; 102 goto common; 103 104 case 'g': 105 value = (newmode & S_IRWXG) >> 3; 106 goto common; 107 108 case 'o': 109 value = newmode & S_IRWXO; 110 common: if (set->cmd2 & CMD2_CLR) { 111 clrval = 112 (set->cmd2 & CMD2_SET) ? S_IRWXO : value; 113 if (set->cmd2 & CMD2_UBITS) 114 newmode &= ~((clrval<<6) & set->bits); 115 if (set->cmd2 & CMD2_GBITS) 116 newmode &= ~((clrval<<3) & set->bits); 117 if (set->cmd2 & CMD2_OBITS) 118 newmode &= ~(clrval & set->bits); 119 } 120 if (set->cmd2 & CMD2_SET) { 121 if (set->cmd2 & CMD2_UBITS) 122 newmode |= (value<<6) & set->bits; 123 if (set->cmd2 & CMD2_GBITS) 124 newmode |= (value<<3) & set->bits; 125 if (set->cmd2 & CMD2_OBITS) 126 newmode |= value & set->bits; 127 } 128 break; 129 130 case '+': 131 newmode |= set->bits; 132 break; 133 134 case '-': 135 newmode &= ~set->bits; 136 break; 137 138 case 'X': 139 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH)) 140 newmode |= set->bits; 141 break; 142 143 case '\0': 144 default: 145 #ifdef SETMODE_DEBUG 146 (void)printf("getmode:%04o -> %04o\n", omode, newmode); 147 #endif 148 return (newmode); 149 } 150 } 151 152 #define ADDCMD(a, b, c, d) \ 153 if (set >= endset) { \ 154 register BITCMD *newset; \ 155 setlen += SET_LEN_INCR; \ 156 newset = realloc(saveset, sizeof(BITCMD) * setlen); \ 157 if (!newset) { \ 158 if (saveset) \ 159 free(saveset); \ 160 saveset = NULL; \ 161 return (NULL); \ 162 } \ 163 set = newset + (set - saveset); \ 164 saveset = newset; \ 165 endset = newset + (setlen - 2); \ 166 } \ 167 set = addcmd(set, (a), (b), (c), (d)) 168 169 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 170 171 void * 172 setmode(const char *p) 173 { 174 register int perm, who; 175 register char op; 176 BITCMD *set, *saveset, *endset; 177 sigset_t sigset, sigoset; 178 mode_t mask; 179 int equalopdone, permXbits, setlen; 180 long perml; 181 182 if (!*p) 183 return (NULL); 184 185 /* 186 * Get a copy of the mask for the permissions that are mask relative. 187 * Flip the bits, we want what's not set. Since it's possible that 188 * the caller is opening files inside a signal handler, protect them 189 * as best we can. 190 */ 191 sigfillset(&sigset); 192 (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset); 193 (void)umask(mask = umask(0)); 194 mask = ~mask; 195 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL); 196 197 setlen = SET_LEN + 2; 198 199 if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL) 200 return (NULL); 201 saveset = set; 202 endset = set + (setlen - 2); 203 204 /* 205 * If an absolute number, get it and return; disallow non-octal digits 206 * or illegal bits. 207 */ 208 if (isdigit(*p)) { 209 perml = strtol(p, NULL, 8); 210 if (perml < 0 || (perml & ~(STANDARD_BITS|S_ISTXT))) { 211 free(saveset); 212 return (NULL); 213 } 214 perm = (mode_t)perml; 215 while (*++p) 216 if (*p < '0' || *p > '7') { 217 free(saveset); 218 return (NULL); 219 } 220 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 221 return (saveset); 222 } 223 224 /* 225 * Build list of structures to set/clear/copy bits as described by 226 * each clause of the symbolic mode. 227 */ 228 for (;;) { 229 /* First, find out which bits might be modified. */ 230 for (who = 0;; ++p) { 231 switch (*p) { 232 case 'a': 233 who |= STANDARD_BITS; 234 break; 235 case 'u': 236 who |= S_ISUID|S_IRWXU; 237 break; 238 case 'g': 239 who |= S_ISGID|S_IRWXG; 240 break; 241 case 'o': 242 who |= S_IRWXO; 243 break; 244 default: 245 goto getop; 246 } 247 } 248 249 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 250 free(saveset); 251 return (NULL); 252 } 253 if (op == '=') 254 equalopdone = 0; 255 256 who &= ~S_ISTXT; 257 for (perm = 0, permXbits = 0;; ++p) { 258 switch (*p) { 259 case 'r': 260 perm |= S_IRUSR|S_IRGRP|S_IROTH; 261 break; 262 case 's': 263 /* 264 * If specific bits where requested and 265 * only "other" bits ignore set-id. 266 */ 267 if (who == 0 || (who & ~S_IRWXO)) 268 perm |= S_ISUID|S_ISGID; 269 break; 270 case 't': 271 /* 272 * If specific bits where requested and 273 * only "other" bits ignore sticky. 274 */ 275 if (who == 0 || (who & ~S_IRWXO)) { 276 who |= S_ISTXT; 277 perm |= S_ISTXT; 278 } 279 break; 280 case 'w': 281 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 282 break; 283 case 'X': 284 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 285 break; 286 case 'x': 287 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 288 break; 289 case 'u': 290 case 'g': 291 case 'o': 292 /* 293 * When ever we hit 'u', 'g', or 'o', we have 294 * to flush out any partial mode that we have, 295 * and then do the copying of the mode bits. 296 */ 297 if (perm) { 298 ADDCMD(op, who, perm, mask); 299 perm = 0; 300 } 301 if (op == '=') 302 equalopdone = 1; 303 if (op == '+' && permXbits) { 304 ADDCMD('X', who, permXbits, mask); 305 permXbits = 0; 306 } 307 ADDCMD(*p, who, op, mask); 308 break; 309 310 default: 311 /* 312 * Add any permissions that we haven't already 313 * done. 314 */ 315 if (perm || (op == '=' && !equalopdone)) { 316 if (op == '=') 317 equalopdone = 1; 318 ADDCMD(op, who, perm, mask); 319 perm = 0; 320 } 321 if (permXbits) { 322 ADDCMD('X', who, permXbits, mask); 323 permXbits = 0; 324 } 325 goto apply; 326 } 327 } 328 329 apply: if (!*p) 330 break; 331 if (*p != ',') 332 goto getop; 333 ++p; 334 } 335 set->cmd = 0; 336 #ifdef SETMODE_DEBUG 337 (void)printf("Before compress_mode()\n"); 338 dumpmode(saveset); 339 #endif 340 compress_mode(saveset); 341 #ifdef SETMODE_DEBUG 342 (void)printf("After compress_mode()\n"); 343 dumpmode(saveset); 344 #endif 345 return (saveset); 346 } 347 348 static BITCMD * 349 addcmd(BITCMD *set, int op, int who, int oparg, u_int mask) 350 { 351 switch (op) { 352 case '=': 353 set->cmd = '-'; 354 set->bits = who ? who : STANDARD_BITS; 355 set++; 356 357 op = '+'; 358 /* FALLTHROUGH */ 359 case '+': 360 case '-': 361 case 'X': 362 set->cmd = op; 363 set->bits = (who ? who : mask) & oparg; 364 break; 365 366 case 'u': 367 case 'g': 368 case 'o': 369 set->cmd = op; 370 if (who) { 371 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) | 372 ((who & S_IRGRP) ? CMD2_GBITS : 0) | 373 ((who & S_IROTH) ? CMD2_OBITS : 0); 374 set->bits = (mode_t)~0; 375 } else { 376 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS; 377 set->bits = mask; 378 } 379 380 if (oparg == '+') 381 set->cmd2 |= CMD2_SET; 382 else if (oparg == '-') 383 set->cmd2 |= CMD2_CLR; 384 else if (oparg == '=') 385 set->cmd2 |= CMD2_SET|CMD2_CLR; 386 break; 387 } 388 return (set + 1); 389 } 390 391 #ifdef SETMODE_DEBUG 392 static void 393 dumpmode(BITCMD *set) 394 { 395 for (; set->cmd; ++set) 396 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 397 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 398 set->cmd2 & CMD2_CLR ? " CLR" : "", 399 set->cmd2 & CMD2_SET ? " SET" : "", 400 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 401 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 402 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 403 } 404 #endif 405 406 /* 407 * Given an array of bitcmd structures, compress by compacting consecutive 408 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 409 * 'g' and 'o' commands continue to be separate. They could probably be 410 * compacted, but it's not worth the effort. 411 */ 412 static void 413 compress_mode(BITCMD *set) 414 { 415 register BITCMD *nset; 416 register int setbits, clrbits, Xbits, op; 417 418 for (nset = set;;) { 419 /* Copy over any 'u', 'g' and 'o' commands. */ 420 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 421 *set++ = *nset++; 422 if (!op) 423 return; 424 } 425 426 for (setbits = clrbits = Xbits = 0;; nset++) { 427 if ((op = nset->cmd) == '-') { 428 clrbits |= nset->bits; 429 setbits &= ~nset->bits; 430 Xbits &= ~nset->bits; 431 } else if (op == '+') { 432 setbits |= nset->bits; 433 clrbits &= ~nset->bits; 434 Xbits &= ~nset->bits; 435 } else if (op == 'X') 436 Xbits |= nset->bits & ~setbits; 437 else 438 break; 439 } 440 if (clrbits) { 441 set->cmd = '-'; 442 set->cmd2 = 0; 443 set->bits = clrbits; 444 set++; 445 } 446 if (setbits) { 447 set->cmd = '+'; 448 set->cmd2 = 0; 449 set->bits = setbits; 450 set++; 451 } 452 if (Xbits) { 453 set->cmd = 'X'; 454 set->cmd2 = 0; 455 set->bits = Xbits; 456 set++; 457 } 458 } 459 } 460